[Mimedefang] thoughts on "nolisting"?

Mark Costlow cheeks at swcp.com
Wed Sep 10 01:45:02 EDT 2008

We had the same problem.  I haven't read about Nolisting yet, but
IMHO the whole concept of backup MX servers has been made almost
pointless by the spammers.  (Pointless, that is, except for helping
spammers do their dirty work).

We found that putting greylisting on the backup MX server did
wonders.  Even in an environment where you can't afford to do
greylisting on the primary MX, it's generally OK to do it on the
backup MX.  Yes, it can delay legitimate mail.  But the backup MX
isn't supposed to get any legitimate mail except in cases where the
primary is not responding, and it's just going to sit on it a while
until the primary wakes up.  So the delay isn't an issue.

We had one machine doing backup MX for a few dozen domains, and we
were ready to scrap and upgrade the hardware because it was sweating
so heavily under the pummelling of spammers.  Greylisting reduced
the load by at least 85% and added years to the life of that server.

My $0.02 ...


On Tue, Sep 09, 2008 at 09:31:00PM -0700, Gary Funck wrote:
> We've grown a bit frustrated by the amount of spam that flows
> through our backup MX server.  Was recently reading about the
> "nolisting" technique,  http://en.wikipedia.org/wiki/Nolisting
> where bogus MX servers (primary and highest numbered backup)
> are set up, in the hopes that dimwitted spam clients will
> bounce off those bogus servers.
> Anyone tried this?  Opinions on pros/cons?
> BTW, it seems to me that more ideal backup MX behavior
> might be for the backup to poll the primary, every minute/so,
> and only open port 25 when it determines that the primary
> isn't available ....
> thanks.
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Mark Costlow    | Southwest Cyberport | Fax:   +1-505-232-7975
cheeks at swcp.com | Web:   www.swcp.com | Voice: +1-505-232-7992

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